Generally, a roller-type one-way clutch has an outer race, an inner race disposed concentrically with the outer race, a plurality of rollers disposed between the outer peripheral surface of the inner race and the inner peripheral cam surface of the outer race and transmitting a torque, a spring in contact with an idle rotation side of the rollers, and others.
In such a configuration, the one-way clutch allows the inner race to rotate only in one direction with respect to the outer race by a cam mechanism which is made up of rollers and a cam surface. That is, the inner race is idly rotated in one direction with respect to the outer race and gives a rotational torque to the outer race through the cam mechanism only in the opposite direction.
In general, the roller-type one-way clutch must have some kind of contrivance to prevent rollers as torque transmission members, or a spring that energizes the roller and others from dropping off from a pocket in an axial direction and in a radial direction in order to secure definite engagement.
In particular, since in a roller-type one-way clutch for two-wheelers, the number of rollers is small (for example, 3 or 6 rollers), there is a possibility of failure to achieve the designed torque capacity unless each roller is securely engaged with each other.
In Japanese Patent Application Laid-Open No. 2003-172377, a holding part is provided to the pocket so that rollers or springs do not drop off to the inner peripheral side of the outer race. However, it does not indicate to prevent them from dropping off in the axial direction. In general, by installing a side plate to the one-way clutch, drop-off in the axial direction is prevented.
The use of the side plate increases the number of components, assembly processes, etc., and may complicate the construction. Therefore, the roller-type one-way clutch that can prevent rollers and springs from dropping off in the axial direction and in the radial direction, without requiring a side plate, has been desired.